Vision I-III Flashcards Preview

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Flashcards in Vision I-III Deck (3)
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1

Monocular deprivation in kittens

After, animal couldn't see out of the eye that was shut. "Use it or lose it" hypothesis
Cortex didn't respond to stimulation of contralateral eye
Cortex loses connections to the deprived eye
Connections are lost for good

2

Binocular deprivation in kittens

DOESN'T produce a nearly silent cortex, as might be expected from the results of monocular deprivation

Instead, primary visual cortex was for the most part normal

The cats, however, were behaviorally blind, which means that higher order visual cells were completely disrupted.

Hypothesis: Competition - active suppression by the active eye - that occurs between converging inputs from each eye in the cortex.

More complicated than "use it or lose it"

3

Deprivation of normal binocular experience by strabismus

Medial rectus cut in one eye of a kitten.

Caused the eye to deviate laterally (strabismus).

Two eyes looked at different parts of the
visual world, but each eye individually received the same amount of normal, crisp, high contrast visual input. The only difference was that, at any instant, each eye
saw a different part of the visual world.

The result in the cortex: very few binocular cells! Almost all cells were driven exclusively by one eye or the other
(there were about equal numbers of each)

Hypothesis: 'cells that fire together wire together'.

It is the synchrony of inputs that leads to stabilized synapses. If the inputs are asynchronous, a competitive struggle ensues, and one of the eyes wins everything, and
the other loses altogether. Thus, with a strabismus, nearly all cells become monocularly driven.